1. Field of the Invention
The present invention relates to a method for manufacturing an organic light emitting display.
2. Discussion of Related Art
In general, after a plurality of pixel portions in an organic light emitting display are formed on a substrate, they are scribed to divide into separate panels. A method for testing whether or not panels are defective can be divided into testing types.
In a first testing type, after a substrate is scribed into separate panels, the panels are separately tested. However, in this testing type, if a circuit wiring forming a panel or a size of the panel varies, testing equipment or a zig required for a test should be changed. Further, because the panels should be separately tested, a performance of the test is deteriorated.
In a second testing type, a substrate is scribed in columns or rows and a test of a stick unit is performed. The testing type envisions that respective panels are formed by a liquid crystal, and include testing pads formed at both sides of a stick in order to perform the test of the stick unit. In particular, a testing process of a stick unit is performed by a naked eye test (or by the naked eye).
In a case of the liquid crystal display, there is a demand for a process of injecting a liquid crystal between an upper substrate and a lower substrate. Items of a characteristic test are centered to perform the naked eye test. Accordingly, although a test is carried in a stick unit, the testing time is not increased. However, in a case of an organic light emitting display, in a state that an organic emission layer is previously formed, in addition to the naked eye test, there is a need for a plurality of other test items (or tests). Accordingly, when a panel of the organic light emitting display is tested in a stick unit, a testing time is increased. As such, there is need to test the panel of the organic light emitting display in a sheet unit.
Hereinafter, a method for manufacturing an organic light emitting display to test the organic light emitting display formed in a sheet unit will be described in more detail.
FIG. 1 is a cross-sectional view showing an organic light emitting display, which is formed in a sheet unit.
With reference to FIG. 1, a plurality of pixel portions 120 are formed on a mother substrate 110, and each of the pixel portions 120 includes one or more organic light emitting diodes. Each of the organic light emitting diodes includes an anode electrode, an emission layer, and a cathode electrode. The anode electrode of the organic light emitting diode is electrically connected to a drain electrode of a thin film transistor. Here, the thin film transistor is formed at a lower surface of an opening of a pixel definition film. The emission layer is formed at an upper portion of the anode electrode. The cathode electrode is formed on the emission layer and the pixel definition film.
When a voltage (which may be predetermined) is applied to the anode electrode and the cathode electrode of the organic light emitting diode, holes injected from the anode electrode are transported to the emission layer through a hole transport layer forming the emission layer. Further, electrons injected from the cathode electrode are injected to the emission layer through an electron transport layer. Here, the electrons and the holes are recombined with each other at the emission layer to generate excitons. As the excitons change from an excited state to a ground state, the emission layer emits light to form images.
Furthermore, a test wiring 130 for testing a panel in a sheet unit is formed at a peripheral part of the mother substrate 110. More particularly, an organic light emitting display mother substrate is a substrate on which display panels can be simultaneously (and/or concurrently) tested on a substrate basis before the substrate is divided into individual panels.
When the test wiring 130 receives an external drive signal, it supplies the external drive signal to lines coupled to a panel to test the panel in a sheet unit. So as to test a plurality of pixel portions formed on the substrate 110 in a sheet unit, a test wiring 130 formed at a peripheral part of the mother substrate 110 is exposed to an exterior, and receives an external signal and is tested on whether or not respective pixel portions 120 are defective. Here, in order to receive the external signal, a sealing substrate 150 arranged at an upper portion of the test wiring 130 is removed to expose the test wiring 130 to the exterior.
However, when the mother substrate 110 is adhered to the sealing substrate 150, a pressure from several tons to several tens of tons is applied to the mother substrate 110 and the sealing substrate 150, thereby causing the sealing substrate 150 to contact the peripheral region of the mother substrate 110 on which the test wiring 130 is formed. When the mother substrate 110 contacts with the sealing substrate 150 as described above, an electrostatic force occurs between the mother substrate 110 and the sealing substrate 150. Accordingly, when the sealing substrate 150 formed at an upper portion of the test wiring 130 is scribed and removed, a surface of the test wiring 130 is damaged, with the result that a sheet test cannot be performed.